1. Field of the Invention
This invention relates to sewing machines in general and more particularly to post-type sewing machines having an underbed thread trimmer.
2. Description of the Prior Art
The use of solenoids or cams for actuating thread trimmers is well known in the prior art. See for example U.S. Pat. No. 3,709,176 to Papajewski et al; U.S. Pat. No. 3,658,021 to Hedegaard et al; U.S. Pat. No. 3,624,735 to Hedegaard; U.S. Pat. No. 3,371,633 to Hedegaard; and U.S. Pat. No. 3,359,933 to Bono. One problem associated with prior known driving mechanisms for underbed thread trimmers is that they are unable to provide long strokes for the trimming blade from a mechanism contained entirely within the feeding post of a post-type sewing machine. Moreover, the prior art trimmer driving mechanisms are not provided with a means for positively disengaging the mechanism to insure that the trimming function is not repeated without a subsequent command. Another problem associated with underbed thread trimmers involves timing the thread trimmer driving mechanism to coincide with an advantageous location of the rotary hook for servering the needle and bobbin threads.